The present invention concerns a tear-off cap for closing bottles. Caps for closing bottles are known made of light weight metal consisting of a disc-shaped top wall surrounded by a circumferential flap engaged about the lip of the bottle opening. Such caps include a central tear-off band that crosses the circumferential flap and extends beyond the flap edge in a pull-out tongue. Sealing of the closure is generally assured by the provision of either a disc-shaped or a ring-shaped gasket placed between the lip of the bottle and the undersurface of the cap top wall. In use, such caps must meet certain requirements among which are that the cap must be easily removable from the neck of the bottle and the cap must be temporarily reusable after initial tear-off.
In an attempt to satisfy these requirements which in practice give rise to contrasting problems, there has been proposed, as seen in British Pat. No. 1320490 published June 13, 1973, a cap with a disc-shaped gasket adhered to the undersurface of the cap top only within a zone diametrically opposite the pull-out tongue and arranged transversely of the tear-off band. In this construction the initial tear-off of the cap is not hindered by tearing through the gasket which instead remains intact and affords subsequent reuse of the cap itself.
One disadvantage with this solution resides in the fact that the reclosable nature of the cap for subsequent usage is basically dependent on the residual elasticity of the metal from which it is made. However, after two or three applications on the bottle, the residual elasticity of the metal is nearly used up and therefore the now unreliable reclosure continues to lose its effectiveness.